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Slope stability of an unsaturated embankment with and without natural pore water salinity subjected to rainfall infiltration
, Article Yantu Lixue/Rock and Soil Mechanics ; Volume 43, Issue 8 , 2022 , Pages 2136-2148 ; 10007598 (ISSN) ; Kolahdooz, A ; Ahmadi, M. M ; Sharif University of Technology
Biodiversity Research Center Academia Sinica
2022
Abstract
Natural soils contain a certain amount of salt in the form of dissolved ions or electrically charged atoms, originated from the long-term erosion by acidic rainwater. The dissolved salt poses an extra osmotic water potential being normally neglected in laboratory measurements and numerical analyses. However, ignorance of salinity may result in overestimation of stability, and the design may not be as conservative as thought. Therefore, this research aims to first experimentally examine the influence of pore water salinity on water retention curve and saturated permeability of natural dispersive loess under saline and desalinated conditions. Second, the measured parameters are used for...
Design of Pavement Subdrainage for Iran
, M.Sc. Thesis Sharif University of Technology ; Tabatabaei, Nader (Supervisor)
Abstract
It is widely recognized today that excess moisture in pavement layers, when combined with heavy truck traffic and moisture-susceptible materials, can reduce the service life. Temperatures below freezing can also contribute to durability problems of saturated materials. A major objective in pavement design is to keep the base, subbase, subgrade, and other susceptible paving materials from becoming saturated or even being exposed to constant high moisture levels over time. The use of subsurface drainage has gained popularity over the past two decades, and many pavement agencies now routinely specify drainable pavement structures to reduce moisture-related problems in avements. In this...
Density-based global sensitivity analysis of sheet-flow travel time: kinematic wave-based formulations
, Article Journal of Hydrology ; Volume 559 , April , 2018 , Pages 556-568 ; 00221694 (ISSN) ; Ataie Ashtiani, B ; Simmons, C. T ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Despite advancements in developing physics-based formulations to estimate the sheet-flow travel time (tSHF), the quantification of the relative impacts of influential parameters on tSHF has not previously been considered. In this study, a brief review of the physics-based formulations to estimate tSHF including kinematic wave (K-W) theory in combination with Manning's roughness (K-M) and with Darcy-Weisbach friction formula (K-D) over single and multiple planes is provided. Then, the relative significance of input parameters to the developed approaches is quantified by a density-based global sensitivity analysis (GSA). The performance of K-M considering zero-upstream and uniform flow depth...
Integrated numerical study of rainfall-induced landslides from initiation to propagation using saturation-based rheological model
, Article Scientia Iranica ; Volume 29, Issue 5 B , 2022 , Pages 2304-2316 ; 10263098 (ISSN) ; Manzari, M. T ; Hajilouy Benisi, A ; Sharif University of Technology
Sharif University of Technology
2022
Abstract
This paper presents an integrated two-dimensional numerical framework for simulating rainfall-induced landslides from instability initiation to post-failure flow. To describe the entire process, three steps are considered in this study: (1) a coupled hydrostability analysis which detects the failure plane using the Finite Element Method (FEM) (pre-failure stage); (2) computing the local rheology of the failed mass (wet sandy soil) based on the water saturation at the onset of failure using the saturation-based rheological model (transition stage); and (3) a continuum-based propagation analysis which solves the flow of the wet material employing the Smoothed Particle Hydrodynamics (SPH)...
Considering the Environmental Effect on the Performance of Vertical Axis
Wind Turbines (VAWT)
,
M.Sc. Thesis
Sharif University of Technology
;
Sattari, Sorna
(Supervisor)
;
Boroushaki, Mehrdad
(Supervisor)
Abstract
This project aims to investigate environmental effect –such as dust and rain- on the performance of a vertical axis wind turbine (VAWT). However, those issues are frequently investigated in the horizontal axis wind turbines, but this subject has not been studied in vertical axis wind turbines. Impact of rain or dust particles on the turbine blades can change the turbine performance. So consideration of the impact of environmental factors on the performance of wind turbines is very important. Vertical axis wind turbines, particularly the straight bladed VAWT are widely used in wind power generation in agricultural and rural lighting and the use of this type of turbines is increasing...
Estimating the Time of Concentration in Small Urban Watersheds (Case Study: Tehran)
, M.Sc. Thesis Sharif University of Technology ; Tajrishy, Masoud (Supervisor)
Abstract
Hydrologic analysis in order to design the collection and transmission structures of urban runoff require some time parameters as input that the accuracy of these analysis is directly sensitive to the accuracy of these parameters. Among these parameters, the time of concentration is the most frequently utilized time parameter and numerous equations for estimating the time of concentration in urban watersheds have been proposed. The purpose of this study is to propose some equations to estimate the time of concentration of overland flow in small urban watersheds with pattern similar to arid and semiarid regions and investigate the effect of using LIDs on reducing the surface runoff....
Probabilistic Stability Analysis of a Railway Embankment on Dispersive Strata Subjected to Periodic Rainfall Conditions with Various Patterns
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
The importance of rainfall pattern in assessing embankment stability and deformation is widely known. However, many studies have examined an embankment with simple rainfall patterns or used average and maximum ones. The importance of diverse rainfall patterns has also been overlooked in the study of divergent soil stability in the previous study. Therefore, the hydraulic properties of a natural soil with and without salinity potential and the stability analysis of the railway embankment located on this type of soil under various rainfall patterns are investigated. The study area is part of the Zahedan Chabahar National Railway Project, which is located on divergent soil and has high...
The Impact of Climate Shock on Child Labor
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholamreza (Supervisor)
Abstract
Precipitation in the water year 1396-1397 is the lowest in the past decade. The present study is conducted during this water year and focuses on the effects of climate variables such as temperature and precipitation on child labor supply between Tir 1397 and Farvardin 1398. Children and household characteristics are also taken into account when evaluating child labor supply using OLS and Logit methods. Estimation results indicate that both child work hours and participation in the job market decline with an increase in precipitation. Furthermore, how much time children spend working or studying is heavily influenced by parents' income. The temperature variable does not have a significant...
Time of concentration of surface flow in complex hillslopes
, Article Journal of Hydrology and Hydromechanics ; Volume 61, Issue 4 , 2013 , Pages 269-277 ; 0042790X (ISSN) ; Saghafian, B ; Talebi, A ; Ardakanian, R ; Sharif University of Technology
Versita
2013
Abstract
Time of concentration (TC) of surface flow in watersheds depends on the coupled response of hillslopes and stream networks. The important point in this background is to study the effects of the geometry and the shape of complex hillslopes on the time of concentration considering the degree of flow convergence (convergent, parallel or divergent) as well as the profile curvature (concave, straight or convex). In this research, the shape factor of complex hillslopes as introduced by Agnese et al. (2007) is generalized and linked to the TC. A new model for calculating TC of complex hillslopes is presented, which depends on the plan shape, the type and degree of profile curvature, the Manning...
Climate change impact assessment on hydrology of Karkheh Basin, Iran
, Article Proceedings of the Institution of Civil Engineers: Water Management ; Volume 166, Issue 2 , 2013 , Pages 93-104 ; 17417589 (ISSN) ; Abrishamchi, A ; Marino, M. A ; Abbasnia, A ; Sharif University of Technology
2013
Abstract
This paper addresses the impacts of climate change on hydrology and water resources in the Karkheh River Basin (KRB), which is the third most productive basin in Iran and has great potential for hydropower generation. The total potential capacity of reservoirs in this basin is more than 15 ×109 Mm3, of which 40% has been built. The sensitivity of the KRB to potential climate change is investigated by simulating basin streamflow response under different climate change scenarios. A conceptual rainfall-runoff model (IHACRES) was first calibrated by using hydrological and streamflow observations. The model was then applied by downscaling two general circulation model outputs (CGCM3 and HadCM3)...
A modeling platform for landslide stability: A hydrological approach
, Article Water (Switzerland) ; Volume 11, Issue 10 , 2019 ; 20734441 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
MDPI AG
2019
Abstract
Landslide events are among natural hazards with many fatalities and financial losses. Studies demonstrate that natural factors such as rainfall and human activities such as deforestation are important causes of triggering a landslide. In this study, an integrated two-dimensional slope stability model, SSHV-2D, is developed that considers various aspects of hydrological effects and vegetation impacts on the stability of slopes. The rainfall infiltration and water uptake of roots change the water content of the unsaturated zone. The temporal and spatial distribution of water content is estimated in the hydrological unit of the developed model. The vegetation unit of the model considers...
The impact of pavement permeability on time of concentration in a small urban watershed with a semi-arid climate
, Article Water Resources Management ; Volume 34, Issue 9 , 2020 , Pages 2969-2988 ; Tajrishy, M ; Jalilvand, E ; Sharif University of Technology
Springer
2020
Abstract
Despite the popularity of the permeable pavements in urban areas in recent years, a few empirical equations have been developed to estimate the time of concentration (Tc) on pervious surfaces, and almost none of them is evaluated over the permeable pavements. In this paper, we aim to investigate the effect of low impact development (LID) on Tc and develop a new equation for estimating overland flow Tc compatible with both permeable and impermeable pavements in small urban watersheds with a semi-arid climate. An experimental model was devised to determine the new equation. Synthetic rainfall (22–40 mm.h−1) was applied to a rectangular shaped (6 m × 1 m) test watershed with an adjustable...
Long Term Seasonal Rainfall and Streamflow Prediction using Regionalization of Ocean- Atmospheric Climatic Variables
, M.Sc. Thesis Sharif University of Technology ; Agha Mohammad Hossein Tajrishi, Massoud (Supervisor)
Abstract
Due to water resources restriction and increase in water demand, optimum use of existing available resources is more essential. This needs accurate prediction of streamflow with lag time from one to several months. In recent decades identification of long term climate variables as predictors of hydrological process has made considerable evolution in climatic predictions and several studies have been made in this field. In this research streamflow volume of Dez Dam in dry season (April to August) has been predicted by using multiple regression models and considering seasonal rainfall data, climate indices and ocean-atmospheric variables including surface temperature of adjacent seas and...
Developing An Integrated System Dynamics - Genetic Algorithm Model: Application to Rainfall-Runoff Modelling
, M.Sc. Thesis Sharif University of Technology ; Abrishamchi, Ahmad (Supervisor)
Abstract
Continuous increase in population which leads to increase in water demand, negative ecological and environmental impacts of dam constructions for supplying water, surface and groundwater pollution and climate change impacts on water cycle are among the major reasons that has made water supply into a crisis specifically in the past two decades. This issue is highlighted in regions with arid or semi-arid climatic conditions. Water demand is the key stimulus in the complex and dynamic water resources system which causes interaction among economical, social and environmental sub systems. These issues together with political challenges led to the introduction of integrated water resources...
Estimation of Rainfall Values by using Soil Moisture as a Natural Measurment with SM2RAIN Algorithm (Case study: Orumia lake Catchment)
, M.Sc. Thesis Sharif University of Technology ; Tajrishy, Masoud (Supervisor)
Abstract
The direct impact of rainfall in human life and its fundamental role in water resources management cause the development of methods and algorithms to estimate the rainfall among the researchers. In the past decades the traditional methods were used to measure the amount of rainfall until the advent of Meteorological Satellites has sparked a revolution in this field. Significant temporal and spatial changes of rainfall and the small number of the synoptic stations caused negative impact on the actual distribution of the amount of rainfall in a vast area. The rainfall satellite data were somewhat overcome by existing deficiencies in Synoptic methods by providing a better rainfall distribution...
Site Selection of Detention Basins to Control Urban Flooding
, M.Sc. Thesis Sharif University of Technology ; Tajrishy, Masoud (Supervisor)
Abstract
Detention basins have been used as one of the Best Management Practices (BMPs) for urban flood control during the last decades. In this study, rainfall-runoff modeling in Darakeh Catchment of Tehran for return periods of 50 and 100 years has been performed using Storm Water Management Model (SWMM). This modeling aims to evaluate the present drainage network in dealing with floods and to identify critical sections. Analytic Hierarchy Process (AHP) was used as analytical framework for siting detention basins considering hydrologic, hydraulics, physiographic and economic factors. First, weights for Criteria have been specified and then, site selection of detention basins has been performed....
Numerical Investigation of the Effects of Environmental Parameters on the Simulation of Spread of Fire in Grasslands
, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan (Supervisor) ; Afshin, Hossein (Co-Supervisor)
Abstract
Fire in Grasslands is one of the most dangerous natural disasters that is uncontrollable at the time of its occurrence and will continue until there is a fundamental change in the conditions of the fire. Fire in Grasslands due to the high density of vegetation can produce a large amount of heat energy in a short time and in a very large area, which alone can cause the spread of fire in Grasslands. Today, numerical studies of fire behaviour and propagation are given more attention than experimental studies due to their lower costs and limitations. In the present study, the numerical simulation of the fire spread with the influence of climate parameters such as humidity, rainfall during fire...
Modeling Of The Climatic Parameters Effect Upon Pavement Performance In Different Regions Of Iran
, M.Sc. Thesis Sharif University of Technology ; Tabatabae, Nader (Supervisor)
Abstract
Environmental conditions have a significant effect on the performance of flexible pavements. External factors such as precipitation, temperature, freeze-thaw cycles, and depth to water table play a key role in defining the extent of the impact the environment effects on pavement performance. All types of pavement distress are either caused or aggravated by the environmental factors. Up until now, pavement design in Iran is done according to the AASHTO 1993, which is based on methods that have evolved from the AASHTO Road Test that was conducted at one specific geographic location. The newly released Mechanistic Empirical Pavement Design Guide (MEPDG) by the addition of climatic input makes...
A numerical study on the effect of salinity on stability of an unsaturated railway embankment under rainfall
, Article 4th European Conference on Unsaturated Soils, E-UNSAT 2020, 19 October 2020 through 21 October 2020 ; Volume 195 , 2020 ; Sadeghi, H ; Ahmadi, M. M ; GDS; VJ Tech ; Sharif University of Technology
EDP Sciences
2020
Abstract
Dispersive soils, as one of the main categories of problematic soils, can be found in some parts of the earth, such as the eastern-south of Iran, nearby the Gulf of Oman. One of the most important factors enhancing the dispersive potential is the existence of dissolved salts in the soil water. The main objective of this study is to explore the influence of water salinity on the instability of a railway embankment due to rainfall infiltration. In order to achieve this goal, the embankment resting on a dispersive stratum is numerically modeled and subjected to transient infiltration flow. The effect of dispersion is simplified through variations in the soil-water retention curve with salinity....
Lake Urmia restoration success story: A natural trend or a planned remedy?
, Article Journal of Great Lakes Research ; Volume 47, Issue 4 , 2021 , Pages 955-969 ; 03801330 (ISSN) ; Parizi, E ; Hosseini, S. M ; Ataie Ashtiani, B ; Sharif University of Technology
International Association of Great Lakes Research
2021
Abstract
Lake Urmia is the second-largest hypersaline lake in the world. There has been a drastic water level drop of 7.2 m from 1995 to 2016. Beginning in October 2013, the Lake Urmia Restoration Plan (LURP) launched a 10-year program. An increase in water level and a relative improvement in Lake Urmia condition has been observed since 2017. It is an undecided and controversial issue whether the recent positive trend of Lake Urmia has been due to the LURP activities or it is a natural contribution of climate factors variations. To shed some light on this issue, we examine three other lakes, adjacent to the Lake Urmia basin, with similar rainfall variability to investigate their status during the...